To make the cake mixture, put the butter and sugar in a mixing bowl and beat them together with an electric handheld whisk until pale and fluffy.

Beat in the vanilla. Add the eggs, a little at a time, beating between each addition (if they are added too quickly, the mixture will separate and the cake won't be as light).

Add the melted white chocolate.

Sift in the flour, then stir it in gently with a metal spoon.

As soon as the ingredients are combined, gently stir in the milk. The mixture should drop easily from the spoon when tapped on the side of the bowl.

Preheat the oven to 180°C/350°F/Gas Mark 4. Grease and line the base and sides of a 23-cm/9-inch square cake tin.

Spoon two-thirds of the cake mixture into the tin and level the surface with the back of the spoon. Bake in the preheated oven for 35 minutes, or until well risen and just firm to the touch.

Leave in the tin for 10 minutes, then transfer to a wire rack to cool. Wash and reline the tin and bake the remaining mixture for 20–25 minutes, as before.

Colour the ready-to-roll icing with a dash of brown food colouring. Roll out half the icing as thinly as possible on a surface lightly dusted with icing sugar.

Cut out 8 rounds using a 7.5-cm/3-inch cookie cutter, re-rolling the trimmings to make sufficient. Repeat with the other half. Dampen the surfaces of the cake cards and position a circle of icing on each.

To make a ganache, heat half the cream in a small saucepan until very hot but not boiling. Pour it into a mixing bowl and add the chocolate. Leave to stand, stirring frequently, until the chocolate has melted. Leave to cool completely.

Stir in the remaining cream and beat lightly with an electric handheld whisk on a slow speed until the ganache is just thick enough to hold its shape (if over-whisked it might start to separate.)

Using a 5-cm/2-inch round cookie cutter as a guide, cut out 16 rounds from the deeper sponge cake. Use a 3-cm/1½-inch round cutter as a guide to cut out 16 rounds from the shallower sponge. (Freeze the trimmings for making trifle or cake pops another time.)

Place the larger cakes on the iced cards, securing with a little ganache. Spread some of the remaining ganache over the tops and sides of these cakes with a palette knife.

Position the smaller cakes on top and cover these with ganache in the same way. Leave to set in a cool place for 1–2 hours.

Cut the ribbon into 60-cm/24-inch lengths and wrap a length around each cake, securing at the tops with bows and cutting off any long ends.